152 



SUBKINGDOM ALGAE: 



Figure 9.2 A stonewort, Chora, about natural size. 



.Nutrition: photosynthetic. 



Reproduction: asexual hy special buds or sexual with 

 sperm produced in male sex organs and eggs in fe- 

 male sex organs (both multicellular sex organs are 

 generally visible and borne upon the "leaves"); sex 

 organs green when young, male organs becoming 

 orange-red when mature and female organs blackish- 

 brown when fertilized; sperm are flagellate, fertiliza- 

 tion is internal; female sex organ drops from plant 

 and develops on fresh-water substrate; life cycle 

 haplobiontic, adult haploid. 



Occurrence: mostly fresh water and submerged 

 upon muddy or sandy bottoms in shallow, standing 

 water, frequently forming dense growth; best devel- 

 opment in clear, hard (usually calcium carbonate) 



fresh water; plants commonly become encrusted with 

 calcium carbonate, hence become an important 

 source of marl (see p. 73) deposition; only a few 

 species are found in brackish water; about 250 spe- 

 cies. 



CHRYSOPHYTA (Golden Algae) 



Structure: mostly unicellular or loosely colonial, 

 also cellular, usually microscopic, and filamentous; 

 form often tends to be amoeboid (see Sarcodina, 

 p. 134) and solitary, or consists of joined, immobile 

 cells with a firm cell wall; cells tend to be naked or in 

 an enveloping membrane; filamentous species are 

 simple and hair-like or branched and tree-like; no 

 tissue tendencies. 



Cells: cells normally distinct, with one to many 

 nuclei; nucleus complete and complex; cytoplasmic 

 pigments normally in yellowish-green to golden- 

 brown, lens- or disc-shaped plastids; pigments also 

 absent; vacuoles often none, or one or more contrac- 

 tile or noncontractile and normally central ones; with 

 or without cell walls; cell walls, when present, often 

 with little cellulose, usually silicified, commonly of 

 two overlapping parts; flagellae none, one, or usually 

 two unequal and dissimilar ones. 



Nutrition: mostly photosynthetic, but most types 

 are represented. 



Reproduction: asexual by mitosis, fragmentation, 

 and spore production; spores include Cyanophyta 

 and Chlorophyta types; some plants develop their 

 spores in sporangia; some plants produce spores of a 

 unique, somewhat complex type; sexual processes in 

 forms other than diatoms are mostly in a seemingly 

 haplobiontic, adult haploid, life cycle; however, 

 diatoms are diplobiontic. 



Occurrence: include a few, mostly fresh-water 

 Chloromonadophyceae of uncertain relationship; 

 about 400 mostly fresh-water or damp soil, but a few 

 marine Xanthophyceae (yellow-green algae); and 

 perhaps 10,000 aquatic Bacillariophyceae (diatoms). 



PHAEOPHYTA (Brown Algae) 



Structure: cellular or tissue organization, branch- 

 ing filaments to more complex; light olive brown to 

 dark brown plants; gametophytes and/or sporophytes 

 vary from minute, irregular groupings of a few cells to 

 complex structures with leaf-like (blades), stem-like 

 (stipes) and root-like (holdfasts) parts resembling 



